Electric resistor terminal



Oct. 23, 1956 l. PASS 2,768,267

ELECTRIC RESISTOR TERMINAL Filed March 8, 1954 MH- "(9 vi? 6 J'J3 14 67 27 an, I

United States Patent ELECTRIC RESISTOR TERMINAL Israel Pass, St. Louis, Mo., assignor to Knapp-Monarch Company, St. Louis, Mo., a corporation of Delaware Application March 8, 1954, Serial No. 414,579

4 Claims. (Cl. 201-67) This invention relates generally to a terminal construction, and more particularly to a terminal construction for use with heating elements of the type including a coiled resistance element centered within a metallic tube and embedded therein in a surrounding matrix of insulating material.

In assemblying heating element constructions of the aforesaid type, the coiled resistance element and its surrounding core of insulation are enclosed within the finned metallic tube and precluded from longitudinal movement therein by means of end plugs or bushings. Such plugs or bushings are generally formed of a ceramic material and provide an anchoring support through which a terminal pin, suitably secured to the coiled resistance element, extends. It is highly important to minimize the risk of breaking the coiled resistance element, and relative movement between the various elements of the construction must be prevented.

It is a primary object of the present invention, therefore, to provide a heat element construction of this general type wherein relative longitudinal and rotational movements between the various elements of the construction, including the metal tube, ceramic bushing, resistance element and core insulation, are precluded.

With these and other objects in view, my invention consists in the construction, arrangement and combination of the various parts of my terminal construction whereby the objects contemplated are obtained as hereinafter more fully set forth, pointed out in my claims and illustrated in the accompanying drawing, wherein:

Figure 1 is an end view of a heating element constructed in accordance with the present invention.

Figure 2 is a cross sectional view in side elevation of the terminal end portion of the construction shown in Figure 1.

Figure 3 is a cross sectional view taken in the direction 33 on Figure 2, showing the cooperative relation between the ceramic bushing and the terminal pin.

Figure 4 is a cross sectional view taken in the direction 4 -4 on Figure 2.

Referring now to the drawing, I have used the numeral to indicate a coiled resistance heating element. The element 10 is embedded within a core or body of insulation material 12. The element 10 and core 12 constitute an integral construction formed in the well-known manner, wherein the coiled element is extruded with a. surrounding mass of plastic insulation material, and subsequently hard fired to provide a rigid assembly. The core 12 is positioned within a metallic tube 14 having a radially outwardly extending helical fin 16.

The core 12 and the tube 14 are arranged in relative longitudinal position by means of a ceramic bushing 18. The bushing 18 is provided with a flange portion 20 and a central axial bore 21. The bushing 18 provides radially extending key portions 22 cooperating with suitable cutouts at the terminal end of the tube 14 2,768,267 Patented Oct. 23, 1956 to lock the two elements against relative rotational movement.

The bushing 18 provides a longitudinally extending end portion 24 having a pair of flat sides 25 and 26. The terminal fin portions 27 and 28 are bent over, as clearly seen in Figs. 1 and 2 to lie upon the flat ledge portion of the bushing 18 which extends peripherally about the longitudinal extension 24. The peripheral edges of the bent over fins 27 and 28 are disposed in contacting engagement with the flats 25 and 26. In this manner, further means in addition to the key portions 22 are provided for precluding relative rotation between the tube 14 and the bushing 18.

The bore 21 of the bushing 18 receives a terminal pin 30 therethrough. The inner end of the pin 30 is slotted to provide a pair of terminal half portions 34 and 36 which are outwardly bent over for locking cooperation with the bushing 18. The pin 30 is provided with an axial bore 32 which extends along the length thereof for a short distance from the point of separation of the bent over half portions 34 and 36. The terminal end of the coiled heating element 10 is received within the bore 32 and secured in position therein by means of crimps 38 in the pin 30.

The inner end of the bushing 18 is provided with a slot 40 having flat sides 41 and 42. The flats 41 and 42 preferably extend in a direction at right angles to the flats 25 and 26 of the outer end of the bushing, as shown. The side edges of the turned over portions 34 and 36 cooperate with the flats 41 and 42 to preclude rotation of the pin 30 relative to the bushing 18.

It will be apparent that by means of the keys 22, and the inwardly bent fins 27 and 28 which cooperate with the flats 25 and 26, the present construction effectively precludes relative rotation between the bushing 18 and the tube 14. Further, by means of the outwardly bent terminal end portions 34 and 36 of the pin 30 in cooperation with the flats 41 and 42 of the recess 40, the present construction efiectively precludes relative rotation between the bushing 18 and the pin 30 and the coiled heating element 10 secured therein.

Changes may be made in the construction and arrangement of the parts of my terminal construction without departing from the real spirit and purpose of my invention, and it is my intention to cover by my claims any modified forms of structure or use of mechanical improvements which may be reasonably included within their scope.

I claim as my invention:

1. A terminal construction comprising a finned metal tube, a. coiled resistance element axially disposed within said tube, an electrical insulating heat conducting material surrounding said resistance element and substantially filling said tube, a bushing disposed within the end of the tube to retain said insulating material against endwise movement, said bushing providing an axial bore therethrough, a terminal pin received within said bushing bore in electrical conducting contact with said resistance element, external portions of said bushing and said tube cooperating to provide a first locking means for precluding relative rotational movement therebe tween, internal portions of said bushing and said pin providing a second locking means for precluding relative rotational movement therebetween.

2. A terminal construction comprising a finned metal tube, a coiled resistance element axially disposed therein, an elongated body of electrical insulating heat conducting material surrounding said resistance element and substantially filling said tube, a bushing disposed within the end of said tube to retain said body therein against endwise movement and providing an axial bore therethrough, a terminal pin disposed within said bushing bore in electrical conducting contact with said resistance element, said bushing having a portion at its outer end providing a pairxlof flat sides, oppositely dis- .posed fin portions ofsaid tube being bent over and cooperating with said fiat sides of the bushing outer .end to preclude relative rotation between the bushing and'the tube, said bushing having a- -portion at itsinner end providing a pair of flatsides, said terminal pin having a pairof radiallyextending portions'at its inner end cooperating with said flatsides of said bushing inner end to preclude relative rotation between the bushing and the pin.

3. A terminal construction comprising afinned metal tube, a coiled resistance element axially disposed therein, an elongated body of electrical insulating heatconducting material surrounding said resistance element and substantially filling said tube, a bushing disposed within the end of said tubeto retainisaid body therein against endwise movementnandproviding an axial bore therethrough, a terminal in disposed within said bushing .bore in electrical conducting contact with said resistance element, said bushing having an extended portion at its outer end providing a pair offlat sides, oppositely disposed fin-portions'of said tube being bent over from cooperating with said fiat sides :of the bushing extension to preclude relative rotation between the bushing and the tube, said bushing having a recessed portion at its inner end providing a pair of flatsides, said terminal pin having a pair of: radially extending portions at .its inner end cooperating with said flat sides of said bushing recess to preclude relative rotation ing and the pin.

4. A terminal construction comprising a finned metal tube, a coiled resistance element axially disposed therein, an elongated body of electrical insulating heat conducting material surrounding said resistance element and substantially filling said tube, a bushing disposed within the end of said tube itoretain said body therein against endwise movement and providing an axial bore therethrough, a terminal pin disposed within said bushingbore and being secured in electrical conductingcontact with .said resistance element,- said bushing having an extended portion at its outer end providing a pair of flat sides, oppositelydisposed 'finportions' of said tube being bent over :and cooperating with said flat sides of the bushing extension to preclude relative rotation between the bushing and the tube, said bushing having a recessed portion at its inner end providing a pair of flatsides, said terminal pin having a pairof radially extending portions at its inner end cooperating with-said .flatsides of said bushing recess' to-preclude relative rotation between the bushing and the-pin, said flat sides of said. bushing recess being disposed in planesperpendicular to those of said flat sides of said bushing exten- SlOIl.

betweenthe bush- References Citedvinthe file of this patent UNITED: STATES'PATENTS 1963328 'Holinger June 19; "I934 

